Circuit breaker with liquid arc quenching



May 21, 1968 E. o. MARX II-ITAL CIRCUIT BREAKER WITH LIQUID ARCQUENCHING Filed March 23, 1965 I 8 4 a w 6 w M 4 a L W o z he i n a 6 a1; 8 3

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Wilfred Kruckewi Ad?! Erk H, Holger Ann, Ludw/ chmifz and Klaus Mall hoff I ATTORNEY$ United States Patent 3,384,724 CIRCUIT BREAKER WITHLIQUEI) ARC QUENCHING Erwin Otto Marx, Brannschweig, Rudolf ErichGrosskope,

Wolfenbuttel, Wilfried Kruckewitt, Braunschweig, Holger Ann,Erlangen-Sieglitzhof, Adil Erlr, Braunschweig, Ludwig Schmitz, Ratingen,and Klaus Mollenhoii, Dortmund-Derne, Germany, assignors to Erwin Marx,Braunschweig, Germany Filed Mar. 23, 1965, Ser. No. 442,016 Claimspriority, application Germany, Apr. 2, 1964,

M 60,516; Feb. 13, 1965, M 64,158

6 Claims. (Cl. 200-150) ABSTRACT OF THE DISCLOSURE Circuit breaker inwhich current carrying contacts are moveable in separating direction ina narrow chamber and adjacent a grating while simultaneously cooling andquenching liquid is caused to flow through the chamber and grating in adirection transverse to the length of the are drawn between the contactmembers as they separate.

The invention relates to an electric liquid switch or circuit breakerhaving an electric arc chamber and means for establishing a transversecurrent of quenching fluid in the chamber to extinguish the arc.

The object of this invention is to construct and improve the abovementioned kind of liquid switch so that it can be used as a high voltageswitch, especially for direct current, and which, if used withalternating current, will effect a considerable shortening of the arcingtime as compared with that of known AC high voltage switches.

The present invention solves this problem by providing a burning chamberwith a narrow end space for the electric are, said are limited in thedirection of movement by an arc-stopping grating of narrow mesh.

By the narrow end space mentioned above is meant a space which islaterally limited in such a manner that the electric arccannot escapetransversely to the direction of flow of the quenching fluid. Because ofthese lateral arc enclosures in combination with a current of quenchingfluid, consisting preferably of oil, the electric arc is effectivelycooled and during its entire time of burning, especially after itssubsequent lengthening, is continuously brought into contact with freshquenching fluid. In consequence of such quenching and lateral enclosureof the are a previously unattained voltage gradient per unit of lengthof the arc is realized. The narrow mesh grating serves to limit themovement of the are after it has become extended to its full length bycontact with the grating and intense cooling by the quenching fluid iscontinued until the arc is completely extinguished. The are is not to bepermitted to strike through the grating and ignite on the outsidethereof where it would largely escape from the restrictive effect of thegrating and the cooling effect of the quenching fluid. Such a strikingthrough of the arc is prevented by providing a grating with a suitablewall structure, in combination with devices such as cooling ribs on theoutside of these walls.

Further objects and advantages of this invention may 3,334,724 PatentedMay 21, 1568 ice become clear from an examination of the followingfigures which show particular embodiments of the invention and are notintended to limit the invention in any way.

The drawings show schematically different modifiications of thisinvention.

FIGURE 1 shows a schematic representation of the new switch having ahorizontally positioned narrow mesh grating wall;

FIGURE 2 is a section along the line II-II of FIGURE 1; and

FIGURES 3 and 4 show details of the grating wall.

In FIGURE 1, 10 is a body of insulating material with a bore 12 in whichpiston 14 is reciprocably sealingly mounted. Piston propelling means,such as the explosive cartridge 16, is operable for impelling piston 14upwardly in bore 12 when actuated.

Bore 12 at its upper end opens into a chamber 18 which tapers outwardlyin the upward direction when viewed in one lateral direction (FIGURE 1)and tapers inwardly in the upward direction when viewed in anotherlateral direction at right angles to the first mentioned lateraldirection (FIGURE 2).

The upper end of chamber 18 is in the form of an elongated slit-likeopening and resting thereon is a grating 20 of insulating material thatmay be made up of the interfitting comb-like parts 22, 24 which areshown assembled in FIGURE 3 and disassembled in FIGURE 4. The gratinghas rather small passages 25 therethrough.

Above grating 20, is a chamber of reservoir 26, which is also preferablyof insulating material. Reservoir 26 at the bottom freely communicateswith the top of grating 20 and at the top has an outwardly opening checkvalve 28.

Body 10 has laterally aligned cylinders 30 and 32 in the upper portionthereof with metal pistons 34 and 36 reciprocably mounted therein.

Projecting from the ends of piston 34, 36 that face each other are thecontact members 38, 40 which, when pistons 34, 36 move toward eachother, will interengage in electrically conductive nature.

The contact members, or electrodes 38, 40 are disposed just beneathgrating 20 so that an are drawn therebetween when piston 34, 36 moveapart and separate the contact members from each other will also bedisposed just beneath the grating.

Wires or rods 42, 44 are connected to and project axially from the sidesof the pistons 34, 36 that face away from each other and these wires orrods are engaged by metal guide rollers 46, 48.

Reservoir 26 contains oil, as indicated at 50. When contact members 38,40 are engaged and piston 14 is at the bottom of bore 12, the oil levelin reservoir 26 is preferably above the upper level of grating 20.

To open the switch while simultaneously extinguishing the are drawnbetween the contact members 38, 40, the piston propelling means isactivated. When the piston propelling means is an explosive cartridge,detonation thereof will impel piston 14 upwardly in bore 12. In anycase, the piston is impelled upwardly in the bore rapidly and the liquidabove piston 14 is displaced from the bore 12.

Part of the displaced liquid will pass through passages 52, 54 to theinner faces of piston 34, 36 and drive the pistons away from each othertoward their FIGURE 1 position and which will simultaneously causecontact members 38,40 to separate and move apart, also toward the FIGURE1 position thereof.

Another part of the liquid driven from bore 12 by piston 14 movesupwardly through chamber 18 and through grating 20 into reservoir 26.This second part of the liquid drives the are between contact members38, 40; the arc being indicated by dashed line 56 in FIGURE 1 and by dot56 in FIGURE 2, upwardly toward the bottom of grating 20 whilesimultaneously coolin the are. In this manner the arc is extinguishedvery quickly and the circuit under the control of the switch isinterrupted with corresponding quickness.

The upper end of piston 14 has a reduced diameter portion 58 which fitsin a reduced diameter upper end portion 60 of bore 12 so that the pistonis cushioned by the liquid in the upper end of the large diameterportion of bore 12 at the top of the piston stroke thereby preventingthe piston from impacting with damaging force against the body at theupper end of the piston stroke.

The new switch construction according to the present invention has anadvantage in that the relatively narrow space for the electric arc inits final position, after the quenching, will be cooled and deionized bythe continued flow of quenching fluid. A recommencement of the electricarc in AC switches after it has once been extinguished is prevented withcertainty.

After studies, calculations and experiments, it was found that animportant requirement is to provide a strong transverse flow of oilacross the electric arc while it is in its final position. The velocityof the quenching fluid must be many times that heretofore used forquenching purposes if the desired average potential gradient of severalthousand volts per cm. along the electric arc is to be reached. Theswitch of this invention is designed in such a manner that the oil flowsthrough the narrowmeshed grating with a velocity greater than 25 m./sec.

Since the walls of the grating which come into contact with the electricare are subjected to severe thermal stresses, it is advisable to formsuch walls of interchange able and preferably separate parts. Such partsmay be comb-like sections assembled to form gratings on the outlet sideand if desired also on the inlet side of the burning chamber.

The grating walls or the built-in parts thereof can be formedadvantageously of a gas-producing insulating substance whereby theuseful life of such substance will be prolonged and the liberated gaswill exert a cooling effect.

In order to expose the entire length of the electric arc to thequenching fluid and to spray it continually from the time it is firstformed, the slot in which the arc is formed is designed to receivequenching fluid along the entire length of the arc and the conduit fordelivering the quenching fluid is connected directly to the burningchamber.

It is advantageous to have the switch break contact directly in front ofthe narrow-meshed grating and to subject the electric arc in the slot ofthe burning chamher to a stream of quenching fluid until it has beenextinguished so as to avoid the formation of excessive voltages.

With such an arrangement there will be no time required for bringing theelectric are into contact with the grating. The entire amount ofquenching fluid will also be available for intense cooling of theelectric arc and where the electric arc will be kept in the slot of theburning chamber by the flow of quenching fluid and will be surrounded onall sides by the flow of quenching fluid around it.

In order to make sure that the electric arcs are traversed by thequenching fluid and are pressed thereby into the narrow slots andagainst the grating walls from the time of their formation, it isimportant that the were.

- i' 4.- I 1 breaking of the contacts and the application of thequenching fluid should be effected simultaneously by the same actuatingmeans.

It is important that the electric arc should be enveloped by the flow ofquenching fluid during the entire burning time of the are so that byintense cooling along the entire length of the arc, as high a voltagecontrol as possible will be produced and maintained.

The electric are always tries to avoid thecurrent of quenching fluid andburn wherever it will not be exposed to the latter. In order tocounteract this tendency of the arc, and especially to prevent the arefrom leaning against the side of the slot, the walls of the latter areprovided with transverse grooves extending to the grating. Since the arcwill not follow the irregular contour of the grooves, it will remain inthe middle of the slot, surrounded by the current of quenching fluid.

The piston by which the quenching fluid is put into motion can beactuatedby an explosive or propulsion charge if the switch is to beopened as quickly as possible for interrupting the DC or AC current asquickly as possible.

For returning the opened switch parts to their closed position, rodsand/or cables can be provided, and also control members such as valveswhich upon rearward movement of the quenching fluid piston permit freshquenching fluid to enter the quenching fluid cylinder and the burningchamber.

It will be understood that this invention is susceptible to modificationin order to adapt it to different usages and conditions and,accordingly, it is desired to comprehend such modifications within thisinvention as may fall within the scope of the appended claims.

What is claimed is:

1. In a circuit breaker; a body with a chamber therein, contact membersinsulatingly supported by the body and moveable in the chamber from afirst position of contact with each other to a second position of spacedrelation to each other, port means for supplying quenching liquid tosaid chamber on one side of the line along which an arc will be drawnbetween said contact members upon separation thereof, a grating in saidbody on the opposite side of said line parallel to and adjacent saidline, means for supplying quenching liquid via said port means to saidone side of said chamber for flow therethrough and through said gratingsimultaneously with movement of said contact members in separatingdirection, said chamher on the said one side of said line taperingoutwardly from said port means to the region of said line in thedirection parallel to said line and tapering inwardly from said portmeans to the region of said line in the direction at right angles tosaid line.

2. A circuit breaker according to claim 1 in which said means forsupplying liquid to said chamber via said port means comprises a bore insaid body communicating with said port means, a piston in the boremoveable toward said port means for causing said supply of liquid .tosaid chamber, piston impelling means for moving the piston in the boretoward said port means, and a reservoir communicating with the side ofsaid grating which faces away from said chamber.

3. A circuit breaker according to claim 2 which includes a cylinder insaid body into which each contact member extends, piston members in saidcylinder substantially smaller in area than the said piston in said boreand connected to respective contact members, and passage meansconnecting said bore with said cylinders so that movement of the pistonin the bore toward said chamber to displace liquid therethrough willcause a simultaneous supply of liquid to said cylinders tourge saidpiston members away from each other thereby to separate said contactmembers.

4. A circuit breaker according to claim 1 in which said grating isformed by a pair of interfitting comb-like members.

5. A circuit breaker according to claim 2 in which said piston is a freepiston and said piston impelling means is carried by said body at theend of said bore which is remote from said port means and is operablefor impelling the said piston in said bore rapidly toward said portmeans 6. A circuit breaker according to claim 5 in which said pistonimpelling means is in the form of an explosive device which, upondetonation, impels said piston toward said port means.

References Cited UNITED STATES PATENTS Baker et al. 200148.3 Sillers200-144 Vogelsanger et al. 200-450 Phillips et a1 200-144 Marx et a1.200-150 10 ROBERT S. MACON, Primary Examiner.

